1. Field of the Invention
The present invention relates to imaging apparatuses having a focus adjustment function such as an electronic still camera and a camcorder and imaging methods therefor.
2. Description of the Related Art
Conventionally, a technology has been known which detects a main subject from a captured screen. For example, a face identified from a feature of the eye or mouth of a human figure or an object identified from its color or luminance level may be detected as a main subject. In this case, the position and size of the main subject may often be output as a detection result.
Another technology has been known which handles a subject at a position touched and designated by a photographer on a touch panel as a main subject. Another technology has been known which handles a subject identified by a photographer by manipulating an operating member such as a four-way operational switch to move an instruction cursor displayed on an image-capturing standby screen as a main subject. The thus detected main subject is used as a target for focusing an imaging lens.
On the other hand, for an autofocus (hereinafter, called AF) function used in an electronic still camera or a camcorder, for example, a method has been used in which a lens position where a high-frequency component of a luminance level signal acquired from an image pick-up device such as a CCD is at a maximum is defined as an in-focus position. In this case, a method has been known in which a main subject detected in the manner as described above is defined as a ranging target area (hereinafter, called a focal-point detection area or an AF frame).
Japanese Patent Laid-Open No. 2004-205885 discloses that the center of a position in an image-capturing range designated by a user is defined as a focal-point detection area.
When still images and moving images are both captured with one camera, control may be switched between optimum modes of an image pick-up device for a still image capturing operation, a moving image capturing operation and an image-capturing standby state. However, when a moving image capturing operation is performed without changing a focal-point detection area set in a moving image-capturing standby state, the focal-point detection area may not possibly be set accurately at a subject position set in the moving image-capturing standby state.
This is caused because the number of pixels readout by the image pick-up device differs in a moving image-capturing standby state and a moving image capturing operation and thus the aspect ratio of the screen may differ.
Furthermore, when a face detected by a camera is to be defined as a main subject, it takes time after switching the control of the image pick-up device until a face detection result is output. Therefore, a face detection result is not acquired immediately after a moving image capturing operation starts, and a focal-point detection area may not possibly be set.